Swift heavy ion-induced interface mixing in a Si–Nb thin film system

Abstract

In this work, we report the study of swift heavy ion-induced mixing at the interface of an a-Si/Nb/ a-Si (a-Si=amorphous silicon) thin film system at different fluences using two different characterization techniques: secondary ion mass spectroscopy and Rutherford backscattering spectrometry. The depth profiles of the samples of this system showed significant changes in the interface region when irradiated by 120 MeV Au ions. The fluence range was varied from 1×10¹³ to 1×10¹⁴ ions/cm². Significant interface mixing has been observed in this range and was found to increase linearly with the increase in the ion fluence. Atomic force microscopy of the samples was also performed to confirm that there is no significant contribution of surface roughness. Mixing has been quantified in terms of mixing rate (k). This high energy-induced mixing effect has been explained in the framework of the thermal spike model which verifies the hypothesis of melt-phase diffusion across the interface.

Keywords:

• ion beam mixing
• swift heavy ions
• electronic energy loss

Acknowledgements

Dr Diva is grateful to the Metallurgy Division, TBRL (DRDO), Chandigarh, for facilitating the completion this work. Dr R.S. Chauhan would like to thank UGC, New Delhi, for the financial support in terms of a project. We are thankful to Dr Pivin (Orsay Campus, France) and Dr D.K. Avasthi of IUAC, Delhi, for their help and suggestions and Ms Neeti Tripathi (Delhi University) for the AFM data.